1. Field
The present disclosure relates generally to communication, and more specifically to techniques for processing symbols for wireless communication.
2. Background
In a wireless communication system, a transmitter may process (e.g., encode, interleave, and symbol map) traffic data to obtain data symbols. The transmitter may further process the data symbols to generate a modulated signal and then transmit this signal via a wireless channel. The transmitted signal may be distorted by the wireless channel and further degraded with noise and interference.
A receiver may receive the transmitted signal and process the received signal to obtain samples. The receiver may then process the samples to obtain detected data symbols, which are estimates of the data symbols sent by the transmitter. The receiver may compute log-likelihood ratios (LLRs) for bits of the data symbols based on the detected data symbols and may then process (e.g., deinterleave and decode) the LLRs to obtain decoded data.
Decoding performance may be dependent on the quality of the LLRs computed based on the detected data symbols. The quality of the LLRs may in turn be dependent on various factors such as fluctuations in the amplitude of the detected data symbols. An automatic gain control (AGC) loop may be used to achieve approximately constant power for the samples in order to obtain approximately constant amplitude for the detected data symbols. However, the AGC loop may not be effective in certain operating scenarios, as described below.